Conventionally, in the field of medical instruments such as endoscopes, a medical instrument is known which includes an insertion portion to be inserted into a body cavity in order to observe or treat a diseased part inside the body cavity (e.g., see PTL 1 and PTL 2).
This medical instrument has a curving portion through which a curvature of the insertion portion is changed by pulling a wire cable disposed inside the insertion portion. Specifically, the curving portion has a structure such that pulling the wire cable causes the side of the curving portion pulled by the wire to be drawn toward the user's hand, which curves the curving portion.